Just found the thread because I was wondering if someone was already working on something like this. I went poking around in the editor (this being my first time) and my heart sank when I saw the way too simple "100" there for status effects on skills and realized the task would be much harder to "fix" the armor CC issue than I thought it would be. Editing the statuses themselves, like you did, is probably too far over my head as I have been out of coding practice for a while, but as a game design/math issue, I have a couple suggestions.
Straight percentages are a good stopgap to making sure the system works (and it was going to be my first step), but in the end, you want to reward characters who have high armor values. For example, if someone has max armor 10 and another has max armor 100, both would be "equally good" at stopping the crowd control. Clearly, the one with 100 should be "better" in some fashion, so tweaking the numbers in their favor could be implemented.
Similarly, the chief complaint many people had (and based on the new system Larian agrees) is that CC was too unavoidable. Their new fix simply delays the same negative gameplay until armor is gone, so maybe a flat x% (let's say 20%) is always able to be resisted. Conversely, that same x% could also always be possible, even if they are sitting at full armor. This would mean that nothing is ever beyond hope, or ever a sure thing, something I think would be a better design. It could offer "war stories" and "stand up and cheer moments" that a story-heavy game could really benefit from, and some number crunch to prevent stun-locking as well.
Finally, and this doesn't exactly pertain to your mod, but it is adjacent, is to have armor only prevent SOME of the damage. Having % chance to have the CC go through just means that stuff happens faster. If, for example, 50% of the damage went to the appropriate armor and the other half went to Vitality, it might keep people in that "maybe-maybe not" sweet spot for longer. It also has the benefit of making healing spells more beneficial throughout the entire fight, rather than just the last half. Armor gaining spells are helpful the whole way through, and so should regular old healing be as well (I'm looking at you, necromancy!). If you really wanted to go crazy, you could have it not be a 50-50 split, and have it based on how they are in proportion to their full value and each other (so someone who is low health but has full armor takes more armor damage and less vitality). But that is probably making it more complicated than it needs to be, and is just more math for math sake (even if it's cool).
